Definition of the control model and perturbed models

  • A technical note (Gagnon et al. 2013) describing the latest modifications made to the global ensemble prediction system (GEPS) is available here
  • The list of reference can be found at the bottom of the page.
  • All members make use of
    1. the GEM model as dynamical core
    2. a global gaussian horizontal computational grid of 600x300 points (0.6 degrees apart, i.e., about 66 km at the equator)
    3. 40 levels of computation in the vertical with a top at 2 hPa
    4. time step of 20 minutes
    5. Canadian Climate Centre for modelling and analysis (CCCma) radiative scheme (Li and Barker, 2005)
    6. ISBA type of land surface processes (Noilhan & Planton, 1989)
    7. Evolving sea surface temperatures using the approach of the persistence of the initial anomaly (1995-2009 climatology)

Description of the physical parameterizations configurations used in the models

The control model

This unperturbed model is initialised with the average of the 192 analyses produced by the Ensemble Kalman Filter (EnKF, see Houtekamer et al. 2014).

model number: 0

  • Parameter for Gravity Wave Drag = 8.0e-6 m-1 (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (consun)
  • Kain & Fritsch (1993) convective scheme
  • Shallow convection simulated (conres & ktrsnt_mg)
  • Bougeault & Lacarràre (1989) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 1.0
  • Parameter of the orographic blocking (Cd) = 1.0

These are the same schemes used by the model of the global deterministic prediction system (GDPS).

The 20 perturbed GEM models

Every perturbed model is initialised with a different analysis generated by the EnKF (see Houtekamer et al. 2014). All perturbed models use a energy back-scattering scheme as well as a stochastic perturbations of the physical tendencies scheme (see description in Charron et al. 2010). The random numbers used in these two stochastic schemes are different for every member and every issue time (unique seeds are used).

model number: 1

  • Parameter for Gravity Wave Drag = 1.2e-5 m-1 , strong (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (consun)
  • Kain & Fritsch (1993) convective scheme
  • Shallow convection simulated (conres & ktrsnt_mg)
  • Blackadar (1962) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 1.0
  • Parameter of the orographic blocking (Cd) = 1.5

model number: 2

  • Parameter for Gravity Wave Drag = 1.2e-5 m-1, strong (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (newsund)
  • Kuo-type convective scheme (oldkuo, Geleyn, 1985)
  • Shallow convection simulated (conres)
  • Blackadar (1962) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 1.0
  • Parameter of the orographic blocking (Cd) = 0.5

model number: 3

  • Parameter for Gravity Wave Drag = 4.0e-6 m-1, weak (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (consun)
  • Kain & Fritsch (1993) convective scheme
  • Shallow convection simulated (conres & ktrsnt_mg)
  • Bougeault & Lacarrère (1989) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 0.85
  • Parameter of the orographic blocking (Cd) = 0.5

model number: 4

  • Parameter for Gravity Wave Drag = 4.0e-6 m-1 , weak (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (newsund)
  • Kuo-type convective scheme (oldkuo, Geleyn, 1985)
  • Shallow convection simulated (conres)
  • Bougeault & Lacarrère (1989) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 0.85
  • Parameter of the orographic blocking (Cd) = 0.5

model number: 5

  • Parameter for Gravity Wave Drag = 4.0e-6 m-1 , weak (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (consun)
  • Kain & Fritsch (1993) convective scheme
  • Shallow convection simulated (conres & ktrsnt_mg)
  • Blackadar (1962) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 1.0
  • Parameter of the orographic blocking (Cd) = 1.5

model number: 6

  • Parameter for Gravity Wave Drag = 4.0e-6 m-1 , weak (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (newsund)
  • Kuo-type convective scheme (oldkuo, Geleyn, 1985)
  • Shallow convection simulated (conres)
  • Blackadar (1962) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 1.0
  • Parameter of the orographic blocking (Cd) = 0.5

model number: 7

  • Parameter for Gravity Wave Drag = 4.0e-6 m-1, weak (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (consun)
  • Kain & Fritsch (1993) convective scheme
  • Shallow convection simulated (conres & ktrsnt_mg)
  • Bougeault & Lacarrère (1989) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 1.0
  • Parameter of the orographic blocking (Cd) = 1.5

model number: 8

  • Parameter for Gravity Wave Drag = 4.0e-6 m-1, weak (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (newsund)
  • Kuo-type convective scheme (oldkuo, Geleyn, 1985)
  • Shallow convection simulated (conres)
  • Bougeault & Lacarrère (1989) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 1.0
  • Parameter of the orographic blocking (Cd) = 0.5

model number: 9

  • Parameter for Gravity Wave Drag = 1.2e-5 m-1, strong (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (consun)
  • Kain & Fritsch (1993) convective scheme
  • Shallow convection simulated (conres & ktrsnt_mg)
  • Bougeault & Lacarrère (1989) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 1.0
  • Parameter of the orographic blocking (Cd) = 1.5

model number: 10

  • Parameter for Gravity Wave Drag = 1.2e-5 m-1, strong (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (newsund)
  • Kuo-type convective scheme (oldkuo, Geleyn, 1985)
  • Shallow convection simulated (conres)
  • Bougeault & Lacarrère (1989) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 1.0
  • Parameter of the orographic blocking (Cd) = 0.5

model number: 11

  • Parameter for Gravity Wave Drag = 1.2e-5 m-1, strong (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (consun)
  • Kain & Fritsch (1993) convective scheme
  • Shallow convection simulated (conres & ktrsnt_mg)
  • Bougeault & Lacarrère (1989) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 0.85
  • Parameter of the orographic blocking (Cd) = 1.5

model number: 12

  • Parameter for Gravity Wave Drag = 1.2e-5 m-1, strong (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (newsund)
  • Kuo-type convective scheme (oldkuo, Geleyn, 1985)
  • Shallow convection simulated (conres)
  • Bougeault & Lacarrère (1989) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 0.85
  • Parameter of the orographic blocking (Cd) = 0.5

model number: 13

  • Parameter for Gravity Wave Drag = 4.0e-6 m-1, weak (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (consun)
  • Kain & Fritsch (1993) convective scheme
  • Shallow convection simulated (conres & ktrsnt_mg)
  • Blackadar (1962) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 0.85
  • Parameter of the orographic blocking (Cd) = 1.5

model number: 14

  • Parameter for Gravity Wave Drag = 4.0e-6 m-1, weak (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (newsund)
  • Kuo-type convective scheme (oldkuo, Geleyn, 1985)
  • Shallow convection simulated (conres)
  • Blackadar (1962) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 0.85
  • Parameter of the orographic blocking (Cd) = 0.5

model number: 15

  • Parameter for Gravity Wave Drag = 1.2e-5 m-1, strong (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (consun)
  • Kain & Fritsch (1993) convective scheme
  • Shallow convection simulated (conres & ktrsnt_mg)
  • Blackadar (1962) (1962) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 0.85
  • Parameter of the orographic blocking (Cd) = 1.5

model number: 16

  • Parameter for Gravity Wave Drag = 1.2e-5 m-1, strong (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (newsund)
  • Kuo-type convective scheme (oldkuo, Geleyn, 1985)
  • Shallow convection simulated (conres)
  • Blackadar (1962) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 0.85
  • Parameter of the orographic blocking (Cd) = 0.5

model number: 17

  • Parameter for Gravity Wave Drag = 1.2e-5 m-1, strong (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (consun)
  • Kain & Fritsch (1993) convective scheme
  • Shallow convection simulated (conres & ktrsnt_mg)
  • Blackadar (1962) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 1.0
  • Parameter of the orographic blocking (Cd) = 0.5

model number: 18

  • Parameter for Gravity Wave Drag = 1.2e-5 m-1, strong (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (newsund)
  • Kuo-type convective scheme (oldkuo, Geleyn, 1985)
  • Shallow convection simulated (conres)
  • Blackadar (1962) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 1.0
  • Parameter of the orographic blocking (Cd) = 1.5

model number: 19

  • Parameter for Gravity Wave Drag = 4.0e-6 m-1, weak (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (consun)
  • Kain & Fritsch (1993) convective scheme
  • Shallow convection simulated (conres & ktrsnt_mg)
  • Bougeault & Lacarrère (1989) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 0.85
  • Parameter of the orographic blocking (Cd) = 1.5

model number: 20

  • Parameter for Gravity Wave Drag = 4.0e-6 m-1, weak (McFarlane, 1987)
  • Sundqvist et al. (1989) type of condensation (newsund)
  • Kuo-type convective scheme (oldkuo, Geleyn, 1985)
  • Shallow convection simulated (conres)
  • Bougeault & Lacarrère (1989) mixing length formulation
  • Turbulent vertical diffusion parameter (Beta) = 0.85
  • Parameter of the orographic blocking (Cd) = 0.5

References

  • Blackadar, A. K. 1962: The Vertical Distribution of Wind and Turbulent Exchange in a Neutral Atmosphere, Journal of Geophysical Research, Vol. 67, No. 8, 1962, pp. 3095-3102.
  • Bougeault, P. and P. Lacarrère, 1989: Parameterization of orography-induced turbulence in a meso-beta-scale model. Mon. Wea. Rev., 117, 1872-1890.
  • Charron, M., G. Pellerin, L. Spacek, P. L. Houtekamer, N. Gagnon, H. L. Mitchell, L. Michelin, 2010: Toward Random Sampling of Model Error in the Canadian Ensemble Prediction System, Mon. Wea. Rev., 138, 1877-1901.
  • Gagnon, N., H. Lin, S. Beauregard, M. Charron, B. Archambault, R. Lahlou and C. Côté, 2013: Improvements to the Global Ensemble Prediction System (GEPS) from version 3.0.0 to version 3.1.0. Canadian Meteorological Centre Technical Note. [Available on request from Environment Canada, Centre Météorologique Canadien, division du développement, 2121 route Transcanadienne, 4e étage, Dorval, Québec, H9P1J3 or via the following web site : http://collaboration.cmc.ec.gc.ca/cmc/CMOI/product_guide/docs/changes_e.html#20131127_geps_3.1.0
  • Geleyn, J.-F. 1985: On a Simple, Parameter-Free Partition between Moistening and Precipitation in the Kuo Scheme., Mon. Wea. Rev., 113, 405-407.
  • Houtekamer, P.L., Deng X., Mitchell H. L., Baek, S.J. and N. Gagnon, 2014: Higher Resolution in an Operational Ensemble Kalman Filter, Mon. Wea. Rev., Early online release: http://journals.ametsoc.org/doi/abs/10.1175/MWR-D-13-00138.1
  • Kain, J.S., and J.M. Fritsch, 1993: Convective parameterization for mesoscale models: The Kain- Fritsch scheme. The representation of cumulus convection in numerical models. Meteor. Monogr., No. 24, Amer. Meteor. Soc., 165-170.
  • Li, J., and H. W. Barker, 2005: A radiation algoritm with correlated-k distribution. Part I: Local thermal equilibrium. J. Atmos. Sci., 62, 286-309.
  • McFarlane, N.A., 1987: The effect of orographically excited gravity-wave drag on the general circulation of the lower stratosphere and troposphere. J. Atmos. Sci., 44, 1775-1800.
  • Noilhan, J. and S. Planton 1989 : A simple parameterization of land surface processes for meteorological models, Mon. Wea. Rev., 117, 536-549.
  • Sundqvist, H., E. Berge and J.E. Kristjansson, 1989: Condensation and cloud parameterization studies with a mesoscale numerical weather prediction model. Mon Wea Rev, 117, 1641--1657.